It is a nonstandard punctuation mark used in various written languages and intended to combine the functions of the question mark (also called the “interrogative point”) and the exclamation mark or exclamation point.

I can’t think of a time when I ask a question when I don’t use an exclamation mark after. Ex: You are stuck in a what?! There is 50% off ice cream until when?!

In the interest of milliseconds, I think blackberry needs to introduce an interrobang key because I seriously use the two all the time!